Solid-state imaging device, method of manufacturing the same, and electronic equipment

ABSTRACT

A solid state imaging device including a semiconductor layer comprising a plurality of photodiodes, a first antireflection film located over a first surface of the semiconductor layer, a second antireflection film located over the first antireflection film, a light shielding layer having side surfaces which are adjacent to at least one of first and the second antireflection film.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority PatentApplication JP 2010-082488 filed in the Japan Patent Office on Mar. 31,2010, the entire contents of which are hereby incorporated by referenceto the extent permitted by law.

BACKGROUND OF THE INVENTION

The present invention relates to a solid-state imaging device, a methodof manufacturing the same, and electronic equipment.

Electronic equipment such as a digital video camera and a digital stillcamera includes a solid-state imaging device. For example, as thesolid-state imaging device, a CMOS (Complementary Metal OxideSemiconductor) type image sensor and a CCD (Charge Coupled Device) typeimage sensor are included.

In the solid-state imaging device, a plurality of pixels is arranged ona surface of a substrate. In each pixel, a photoelectric conversionportion is provided. The photoelectric conversion portion is, forexample, a photo diode, and creates a signal electric charge byreceiving an incident light by a light sensing surface to perform thephotoelectric conversion.

Among the solid-state imaging devices, in the CMOS type image sensor,the pixels are configured to include a pixel transistor in addition tothe photoelectric conversion portion. The pixel transistor is configuredto read the signal electric charge created in the photoelectricconversion portion and output the read signal electric charge to asignal line as an electric signal.

In the solid-state imaging device, generally, the photoelectricconversion portion receives the light that is incident from the frontsurface side on which a circuit element, a wiring or the like isprovided on the substrate. In this case, since the circuit element, thewiring or the like shields or reflects the incident light, it isdifficult to improve the sensitivity.

For this reason, there is proposed a “rear surface irradiation type”(e.g., see Japanese Unexamined Patent Application Publication Nos.2003-31785, 2005-347707, 2005-35363, and 2005-353955) in which thephotoelectric conversion portion receives the light that is incidentfrom a rear surface side being an opposite side of a front surface onwhich the circuit element, the wiring or the like is provided in thesubstrate.

However, in order to suppress an occurrence of dark current due to aninterface state of the semiconductor with the photoelectric conversionportion provided thereon, it is disclosed that the photoelectricconversion portion has a HAD (Hole Accumulation Diode) structure. In theHAD structure, by forming a positive electric charge accumulation (hole)accumulation area on the light sensing surface of an n-type of electriccharge accumulation area, the occurrence of the dark current issuppressed.

In order to form the positive electric charge accumulation area in aninterface portion of the photoelectric conversion portion, it isproposed that, by providing “a film having a negative fixed electriccharge” on the light sensing surface of the n-type of electric chargeaccumulation area and peeling the same, the occurrence of dark currentis suppressed. Herein, a high dielectric film having a high refractiveindex such as a hafnium oxide film (a HfO₂ film) is used as a “filmhaving a negative fixed electric charge” to suppress the occurrence ofdark current, and the hafnium oxide film is used as an antireflectionfilm to realize the high sensitivity (e.g., see Japanese UnexaminedPatent Application Publication No. 2007-258684 (paragraphs 0163 to 0168)and Japanese Unexamined Patent Application Publication No. 2008-306154(paragraph 0044 or the like)).

SUMMARY

One embodiment consistent with the present invention includes asemiconductor layer comprising a plurality of photodiodes, a firstantireflection film located over a first surface of the semiconductorlayer, a second antireflection film located over the firstantireflection film, a light shielding layer having side surfaces whichare adjacent to at least one of first and the second antireflectionfilm.

In another embodiment consistent with the present invention, the lightshielding layer is located between the first antireflection film and thesecond antireflection film.

In another embodiment consistent with the present invention, anintermediate layer located between the first antireflection film and thelight shielding layer.

In another embodiment consistent with the present invention, the lightshielding layer is embedded in the second antireflection film.

In another embodiment consistent with the present invention a separationregion is included between each of the plurality of photodiodes.

In another embodiment consistent with the present invention, the lightshielding layer is located over the separation region.

In another embodiment consistent with the present invention, a trench islocated in each of the separation regions where the light shieldinglayer is located inside the trench.

In another embodiment consistent with the present invention, thephotodiode has a first surface which receives light.

In another embodiment consistent with the present invention, the firstantireflection film and the second antireflection film are located overthe first surface of the photodiode.

In another embodiment consistent with the present invention, thethickness of the first antireflection film is smaller than the thicknessof the second antireflection film.

In another embodiment consistent with the present invention, the lightshielding layer has a substantially convex shape.

In another embodiment consistent with the present invention, the firstantireflection film includes at least one of an oxide of hafnium,zirconium, aluminum, tantalum, titanium, magnesium, yttrium, lanthanoidor silicon element.

In another embodiment consistent with the present invention, the secondantireflection film includes at least one of an oxide of hafnium,zirconium, aluminum, tantalum, titanium, magnesium, yttrium, lanthanoidor silicon element.

In another embodiment consistent with the present invention, the firstantireflection film has a refraction index of 1.5 or more.

In another embodiment consistent with the present invention, the secondantireflection film has a refraction index of 1.5 or more

In another embodiment consistent with the present invention, the solidstate imaging device includes a wiring layer located over a secondsurface of the semiconductor layer opposite the first antireflectionfilm and the second antireflection film.

In another embodiment consistent with the present invention, the solidstate imaging device includes a transistor located over the secondsurface of the semiconductor layer.

In another embodiment consistent with the present invention, thetransistor transfers an electric charge from the photodiode to atransmission line.

Another embodiment consistent with the present embodiment includes amethod for manufacturing a solid state imaging device comprising thesteps of forming a semiconductor layer comprising a plurality ofphotodiodes, forming a first antireflection film over a first surface ofthe semiconductor layer, forming a second antireflection film over thefirst antireflection film, forming a light shielding layer having sidesurfaces, where the side surfaces are adjacent to at least one of thefirst antireflection film and the second antireflection film.

In another embodiment consistent with the present invention, the secondantireflection film is formed after forming the light shielding layer.

In another embodiment consistent with the present invention, the lightshielding layer is formed after forming the second antireflection film.

In another embodiment consistent with the present invention, the lightshielding layer is located between the first antireflection film and thesecond antireflection film.

In another embodiment consistent with the present invention, the methodincludes the step of forming an intermediate layer located between thefirst antireflection film and the light shielding layer.

In another embodiment consistent with the present invention, the lightshielding layer is embedded in the second antireflection film.

In another embodiment consistent with the present invention, the methodincludes the step of forming a separation region between each of theplurality of photodiodes.

In another embodiment consistent with the present invention, the lightshielding layer is located over the separation region.

In another embodiment consistent with the present invention, the methodincludes forming a trench located in each of the separation regions,wherein the light shielding layer is located inside the trench.

In another embodiment consistent with the present invention, thephotodiode has a first surface which receives light.

In another embodiment consistent with the present invention, the firstantireflection film and the second antireflection film are located overthe first surface of the photodiode.

In another embodiment consistent with the present invention, thethickness of the first antireflection film is smaller than the thicknessof the second antireflection film.

In another embodiment consistent with the present invention, the lightshielding layer has a substantially convex shape.

In another embodiment consistent with the present invention, the firstantireflection film includes at least one of an oxide of hafnium,zirconium, aluminum, tantalum, titanium, magnesium, yttrium, lanthanoidor silicon element.

In another embodiment consistent with the present invention, the secondantireflection film includes at least one of an oxide of hafnium,zirconium, aluminum, tantalum, titanium, magnesium, yttrium, lanthanoidelement or silicon.

In another embodiment consistent with the present invention, the firstantireflection film has a refraction index of 1.5 or more.

In another embodiment consistent with the present invention, the secondantireflection film has a refraction index of 1.5 or more.

In another embodiment consistent with the present invention, the step offorming a wiring layer over a second surface of the semiconductor layeropposite the first antireflection film and the second antireflectionfilm.

In another embodiment consistent with the present invention, includingthe steps of forming a transistor over the second surface of thesemiconductor layer.

In another embodiment consistent with the present invention, thetransistor transfers an electric charge from the photodiode to atransmission line.

Another embodiment consistent with the present invention, an electronicapparatus including a semiconductor layer including a plurality ofphotodiodes, a first antireflection film on a first surface of thesemiconductor layer, a second antireflection film over the firstantireflection film, a light shielding layer adjacent the firstantireflection film, and a photodiode layer having a side surfaceadjacent at least the second antireflection film.

In the present invention, the first antireflection film is provided soas to cover the portion in which the light sensing surface and the lightshielding layer are provided on the rear surface of the semiconductorlayer. Along with this, the second antireflection film is formed on thefirst antireflection film so as to cover the portion in which the lightsensing surface is provided on the rear surface. The light shieldinglayer 60 is provided not on the second antireflection film but on thefirst antireflection film.

According to an embodiment of the present invention, it is possible toprovide a solid-state imaging device, a method of the manufacturing thesame, and electronic equipment capable of improving an image quality orthe like of a captured image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram showing a configuration of a camera ina first embodiment according to the present invention;

FIG. 2 is a block diagram showing the overall configuration of asolid-state imaging device in the first embodiment according to thepresent invention;

FIG. 3 is a diagram showing a principal part of the solid-state imagingdevice in the first embodiment according to the present invention;

FIG. 4 is a diagram showing a principal part of the solid-state imagingdevice in the first embodiment according to the present invention;

FIG. 5 is a diagram showing a principal part of the solid-state imagingdevice in the first embodiment according to the present invention;

FIG. 6 is a diagram showing a method of manufacturing the solid-stateimaging device in the first embodiment according to the presentinvention;

FIG. 7 is a diagram showing a method of manufacturing the solid-stateimaging device in the first embodiment according to the presentinvention;

FIG. 8 is a diagram showing a method of manufacturing the solid-stateimaging device in the first embodiment according to the presentinvention;

FIG. 9 is a diagram showing a method of manufacturing the solid-stateimaging device in the first embodiment according to the presentinvention;

FIG. 10 is a diagram showing a method of manufacturing the solid-stateimaging device in the first embodiment according to the presentinvention;

FIG. 11 is a diagram showing a principal part of a solid-state imagingdevice in a second embodiment according to the present invention;

FIG. 12 is a diagram showing a method of manufacturing the solid-stateimaging device in the second embodiment according to the presentinvention;

FIG. 13 is a diagram showing a method of manufacturing the solid-stateimaging device in the second embodiment according to the presentinvention;

FIG. 14 is a diagram showing a method of manufacturing the solid-stateimaging device in the second embodiment according to the presentinvention;

FIG. 15 is a diagram showing a principal part of a solid-state imagingdevice in a third embodiment according to the present invention;

FIG. 16 is a diagram showing a principal part of a solid-state imagingdevice in a fourth embodiment according to the present invention; and

FIG. 17 is a cross-sectional view showing a principal part of a pixel Pof a “rear surface irradiation type” of a CMOS image sensor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments consistent with principles of the present invention will bedescribed with reference to the drawings.

Furthermore, the description will be provided in the following order.

1. First Embodiment (a Case of Covering an Upper Surface of a LightShielding Layer)

2. Second Embodiment (a case of providing an intermediate layer in thecase of covering the upper surface of the light shielding layer)

3. Third Embodiment (a case of not covering the upper surface of thelight shielding layer)

4. Fourth Embodiment (a light shielding layer embedment type)

FIG. 17 is a cross-sectional view illustrating a principal part of apixel P of a “rear surface irradiation type” of a CMOS image sensor.

As shown in FIG. 17, in the “rear surface irradiation type” of CMOSimage sensor, a photodiode 21 is provided in a portion that is dividedby a pixel separation portion 101 pb in an inner portion of asemiconductor layer 101.

Although it is not shown in FIG. 17, a pixel transistor is provided on afront surface (a lower surface in FIG. 17) of the semiconductor layer101, and, as shown in FIG. 17, a wiring layer 111 is provided so as tocover the pixel transistor. In addition, a support substrate SS isprovided on the front surface of the wiring layer 111.

Contrary to this, on the rear surface (an upper surface in FIG. 17) ofthe semiconductor layer 101, an antireflection film 50J, a lightshielding layer 60J, a color filter CF, and a micro lens ML areprovided, and the photodiode 21 receives the incident light H that isincident via the respective portions.

Herein, as shown in FIG. 17, the antireflection film 50J covers the rearsurface (the upper surface) of the semiconductor layer 101. Theantireflection film 50J is formed by using a high dielectric having anegative fixed electric charge so that the occurrence of the darkcurrent is suppressed by forming the positive electric chargeaccumulation (hole) accumulation area on the light sensing surface JS ofthe photodiode 21. For example, a hafnium oxide film (HfO₂ film) isprovided as the antireflection film 50J.

As shown in FIG. 17, the light shielding layer 60J is formed on theupper surface of the antireflection film 50J via an interlayerinsulation film SZ. Herein, the light shielding layer 60J is provided atan upper part of the pixel separation portion 101 pb provided in theinner portion of the semiconductor layer 101.

In addition, the upper surface of the light shielding layer 60J iscovered with a planarization film HT, and the color filter CF and themicro lens ML are provided on the upper surface of the planarizationfilm HT. In the color filter CF, for example, each of filter layers ofthree primary colors are arranged for each pixel P in a Bayerarrangement.

In the case of the above-mentioned structure, since the incident lightH, which was incident to one pixel P, is not incident to the photodiode21 of the one pixel P but penetrates the lower part of the lightshielding layer 60J, the incident light H is incident to the photodiode21 of another adjacent pixel P in some cases. That is, in a case wherethe incident light H is incident so as to be greatly sloped with respectto a direction z perpendicular to the light sensing surface JS, theincident light H is not incident to the light sensing surface JSimmediately below that, but incident to the light sensing surface JS ofanother pixel P receiving originally the light of another color. Forthis reason, a so-called “mixed color” is generated, and a colorreproducibility declines in the captured color image, whereby the imagequality declines.

In this manner, in the case of the above-mentioned configuration, adisadvantage such as “mixed color” occurs by leakage of the inclinedlight, and therefore, it is difficult to improve the image quality ofthe captured image.

Thus, it is desirable to provide a solid-state imaging device, a methodof manufacturing the same, and electronic equipment that can improve theimage quality or the like of the captured image.

1. FIRST EMBODIMENT

(FIG. 1 is a configuration diagram showing a configuration of a camera40 in a first embodiment according to the present invention.

As shown in FIG. 1, the camera 40 has a solid-state imaging device 1, anoptical system 42, a control portion 43, and a signal processing circuit44. Each of the portions will be sequentially described.

The solid-state imaging device 1 creates a signal electric charge, byreceiving a light H that is incident via an optical system 42 by animaging surface PS to perform a photoelectric conversion. Herein, thesolid-state imaging device 1 is driven based on the control signal thatis output from a control portion 43 outputs it as raw data.

The optical system 42 includes an optical member such as an imaging lensor an aperture, and is disposed so as to concentrate the light H due toan incident subject image to an imaging surface PS of the solid-stateimaging device 1.

The control portion 43 outputs various control signals to thesolid-state imaging device 1 and the signal processing circuit 44,controls and drives the solid-state imaging device 1 and the signalprocessing circuit 44.

The signal processing circuit 44 is configured so as to create thedigital image with respect to the subject image by performing the signalprocessing with respect to the electric signal that was output from thesolid-state imaging device 1.

(1-2) Principal Part Configuration of Solid-State Imaging Device

The overall configuration of the solid-state imaging device 1 will bedescribed.

FIG. 2 is a block diagram showing the overall configuration of thesolid-state imaging device 1 in a first embodiment according to thepresent invention.

The solid-state imaging device 1 of the present embodiment is a CMOStype image sensor and includes a plate-shaped semiconductor layer 101 asshown in FIG. 2. For example, the semiconductor layer 101 is a singlecrystal silicon semiconductor, and has a pixel area PA and a surroundingarea SA provided thereon.

As shown in FIG. 2, the pixel area PA has a rectangular shape, and aplurality of pixels P are disposed in a horizontal direction x and avertical direction y, respectively. That is, the pixels P are arrangedin a line in the shape of a matrix.

In the pixel area PA, each pixel P is configured so as to receive theincident light to create the signal electric charge. In addition, thecreated signal electric charge is read by a pixel transistor (not shown)and output as the electric signal. The detailed configuration of thepixel P will be described later.

As shown in FIG. 2, the surrounding area SA is situated around the pixelarea PA. In addition, a surrounding circuit is provided in thesurrounding area SA.

Specifically, as shown in FIG. 2, a vertical drive circuit 13, a columncircuit 14, a horizontal drive circuit 15, an external output circuit17, a timing generator (TG) 18, and a shutter drive circuit 19 areprovided as the surrounding circuits.

As shown in FIG. 2, the vertical drive circuit 13 is provided at a sideportion of the pixel area PA in the surrounding area SA and configuredso as to select and drive the pixels P of the pixel area PA in a lineunit.

As shown in FIG. 2, the column circuit 14 is provided at a lower endportion of the pixel area PA in the surrounding area SA and carries outthe signal processing with respect to the signal that is output from thepixels P in the line unit. Herein, the column circuit 14 includes a CDS(Correlated Double Sampling) circuit (not shown) and carries out thesignal processing that removes the fixed pattern noise.

As shown in FIG. 2, the horizontal drive circuit 15 is electricallyconnected to the column circuit 14. The horizontal drive circuit 15includes, for example, a shift register and sequentially outputs thesignals, which are maintained for each row of pixels P in the columncircuit 14, to the external output circuit 17.

As shown in FIG. 2, the external output circuit 17 is electricallyconnected to the column circuit 14, carries out the signal processingwith respect to the signal that was output from the column circuit 14,and then outputs the signal to the outside. The external output circuit17 includes an AGC (Automatic Gain Control) circuit 17 a and an ADCcircuit 17 b. In the external output circuit 17, after the AGC circuit17 a applies the gain to the signal, the ADC circuit 17 b transforms thesignal from an analog signal to a digital signal and the transformedsignal output to the outside.

As shown in FIG. 2, the timing generator 18 is electrically connected toeach of the vertical drive circuit 13, the column circuit 14, thehorizontal drive circuit 15, the external output circuit 17, and theshutter drive circuit 19. The timing generator 18 creates and outputsvarious timing signals to the vertical drive circuit 13, the columncircuit 14, the horizontal drive circuit 15, the external output circuit17, and the shutter drive circuit 19, thereby carrying out the drivecontrol with respect to each part.

The shutter drive circuit 19 is configured so as to select the pixels Pin the line unit and regulate the light exposure time in the pixels P.

(1-3) Detailed Configuration of Solid-State Imaging Device

The detailed content of the solid-state imaging device according to anembodiment of the present invention will be described.

FIGS. 3 to 5 are diagrams showing a principal part of a solid-stateimaging device in a first embodiment according to the present invention.

FIG. 3 is a cross-sectional view of a pixel P. In addition, FIG. 4 is atop plane view of the pixel P formed on the semiconductor substrate.Furthermore, FIG. 5 shows the circuit configuration of the pixel P.Moreover, FIG. 3 shows a cross-section of III-III portion shown in FIG.4.

As shown in FIG. 3, the solid-state imaging device 1 has a photodiode 21provided in the inner portion of the semiconductor layer 101. Forexample, the photodiode 21 is provided on the semiconductor substratethat was thinned to a thickness of about 10 to 24 μm.

On a front surface (a lower surface in FIG. 3) of the semiconductorlayer 101, although it is not shown in FIG. 3, a pixel transistor Tr,such as the pixel transistor depicted in FIGS. 4 and 5, is provided. Inaddition, as shown in FIG. 3, a wiring layer 111 is provided so as tocover the pixel transistor Tr, and a support substrate SS is provided onan opposite surface with respect to the semiconductor layer 101 in thewiring layer 111.

On a rear surface (an upper surface in FIG. 3) of the semiconductorlayer 101, an antireflection film 50, a light shielding layer 60, acolor filter CF, and a micro lens ML are provided, and the photo diode21 receives the incident light H is incident from the rear surface side.

Consistent with this embodiment, the solid-state imaging device 1 of thepresent embodiment is a “rear surface irradiation type CMOS imagesensor” and is formed to receive the incident light H at the rearsurface (the upper surface in FIG. 3) side being the opposite side ofthe front surface (the lower surface in FIG. 3) side.

(a) Photodiode 21

In the solid-state imaging device 1, a plurality of the photodiodes 21are disposed such that each photodiode corresponds to a plurality ofpixels P shown in FIG. 2. That is, on the imaging surface (xy surface),a horizontal direction x and a vertical direction y perpendicular to thehorizontal direction x are provided in a line, respectively.

The photodiode 21 is configured so as to accumulate the signal electriccharge by receiving the incident light H (the subject image) andperforming the photoelectric conversion.

Herein, as shown in FIG. 3, the photodiode 21 receives the lightincident from the rear surface (the upper surface in FIG. 3) side of thesemiconductor layer 101. At an upper part of the photodiode 21, as shownin FIG. 3, the antireflection film 50, the planarization film HT, thecolor filter CF, and the micro lens ML are provided, and the photodiode21 receives the incident light H which was sequentially incident via therespective portions and performs the photoelectric conversion.

As shown in FIG. 3, the photodiode 21 is provided in the semiconductorlayer 101 as a single crystal silicon semiconductor. Specifically, thephotodiode 21 includes an n-type electric charge accumulation area (notshown). In addition, a hole accumulation area (not shown) is formed soas to suppress the occurrence of the dark current in each interfacebetween the upper surface side and the lower surface side of the n typeelectric charge accumulation area.

As shown in FIG. 3, in an inner portion of the semiconductor layer 101,there is provided a pixel separation portion 101 pb in which p typeimpurities are diffused so as to electrically separate between theplurality of pixels P, and the photodiode 21 is provided at an areapartitioned by the pixel separation portion 101 pb.

For example, as shown in FIG. 4, the pixel separation portion 101 pb isformed so as to be interposed between the plurality of pixels P. Thatis, the pixel separation portion 101 pb is formed so that the planeshape thereof becomes a grid shape, and shown in FIG. 4, the photodiode21 is formed in the area partitioned by the pixel separation portion 101pb.

In addition, as shown in FIG. 5, each photodiode 21 is configured sothat an anode is grounded and the accumulated signal electric charge(herein, electron) is read by the pixel transistor Tr and output to avertical signal line 27 as the electric signal.

(b) Pixel Transistor Tr

In the solid-state imaging device 1, a plurality of pixel transistors Tris provided so as to correspond to the plurality of pixels P shown inFIG. 2.

As shown in FIGS. 4 and 5, the pixel transistor Tr includes atransmission transistor 22, an amplification transistor 23, a selectiontransistor 24, and a reset transistor 25 and is configured to read thesignal electric charge from the photodiode 21 and outputs the same asthe electric signal. For example, as shown in FIG. 4, the pixeltransistor Tr is provided so as to be situated at the lower part of thephotodiode 21 in the imaging surface (xy surface).

Each of the transistors 22 to 25 constituting the pixel transistor Trare not shown in FIG. 3 but are provided on the front surface on whichthe wiring layer 111 is provided in the semiconductor layer 101. Forexample, each of the transistors 22 to 25 are provided in the pixelseparation portion 101 pb that separates between the pixels P in thesemiconductor layer 101. For example, each of the transistors 22 to 25are MOS transistors of N channel, and each gate is formed using, forexample, polysilicon. In addition, each of the transistors 22 to 25 iscovered with the wiring layer 111.

As shown in FIGS. 4 and 5, in the pixel transistor Tr, the transmissiontransistor 22 is configured so as to transmit the signal electric chargecreated in the photodiode 21 to a floating and diffusion FD.

Specifically, as shown in FIGS. 4 and 5, the transmission transistor 22is provided between a cathode of the photodiode 21 and the floating anddiffusion FD. In addition, in the transmission transistor 22, thetransmission line 26 is electrically connected to the gate. In thetransmission transistor 22, the transmission signal TG is given from thetransmission line 26 to the gate, thereby transmitting the signalelectric charge accumulated in the photodiode 21 to the floating anddiffusion FD.

As shown in FIGS. 4 and 5, in the pixel transistor Tr, the amplificationtransistor 23 is configured so as to amplify and output the electricsignal which was transformed from the electric charge to the voltage inthe floating and diffusion FD.

Specifically, as shown in FIG. 4, the amplification transistor 23 isprovided between the selection transistor 24 and the reset transistor25. Herein, as shown in FIG. 5, in the amplification transistor 23, thegate is electrically connected to the floating and diffusion FD.Furthermore, in the amplification transistor 23, the drain iselectrically connected to a power supply line Vdd and the source iselectrically connected to the selection transistor 24. When theselection transistor 24 is selected to become in the ON state, theamplification transistor 23 is supplied with the constant current from aconstant electric source I and operated as a source follower. For thisreason, in the amplification transistor 23, the selection signal issupplied to the selection transistor 24, whereby the electric signal,which was transformed from the electric charge to the voltage, isamplified in the floating and diffusion FD.

In the pixel transistor Tr, the selection transistor 24 is configured tooutput the electric signal, which was output by the amplificationtransistor 23, to the vertical signal line 27 when the selection signalis input, as shown in FIGS. 4 and 5.

Specifically, as shown in FIG. 4, the selection transistor 24 isprovided so as to be close to the amplification transistor 23.Furthermore, as shown in FIG. 5, in the selection transistor 24, thegate is connected to an address line 28 that is supplied with theselection signal. In addition, the selection transistor 24 enters the ONstate upon being supplied with the selection signal, and outputs theoutput signal amplified by the amplification transistor 23 as above tothe vertical signal line 27.

In the pixel transistor Tr, as shown in FIGS. 4 and 5, the resettransistor 25 is configured so as to reset the gate electric potentialof the amplification transistor 23.

Specifically, as shown in FIG. 4, the reset transistor 25 is provided soas to be close to the amplification transistor 23. As shown in FIG. 5,in the reset transistor 25, the gate is electrically connected to areset line 29 that is provided with the reset signal. Moreover, in thereset transistor 25, the drain is electrically connected to the electricpower supply line Vdd and the source is electrically connected to thefloating and diffusion FD. In addition, when the reset signal issupplied from the reset line 29 to the gate, the reset transistor 25resets the gate electric potential of the amplification transistor 23 tothe power supply voltage via the floating and diffusion FD.

In the above, the transmission line 26, the address line 28, and thereset line 29 are wired so as to be connected to the gates of therespective transistors 22, 24, and 25 of the plurality of pixels Parranged in the horizontal direction H (a line direction). For thisreason, the operations of the respective transistors 22, 23, 24, and 25are concurrently performed with respect to the pixels P of one line.

(c) Wiring Layer 111

In the solid-state imaging device 1, as shown in FIG. 3, the wiringlayer 111 is provided on the front surface (the lower surface in FIG. 3)being the opposite side of the rear surface (the upper surface in FIG.3) on which each part such as the antireflection film 50 is provided inthe semiconductor layer 101.

The wiring layer 111 includes a wiring 111 h and an insulation layer 111z, and is configured so that the wiring 111 h is electrically connectedto each element in the insulation layer 111 z. Herein, each wiring 111 his stacked and formed in the insulation layer 111 z so as to function aseach wiring such as the transmission line 26, the address line 28, thevertical signal line 27, and the reset line 29, which are shown in FIG.5.

In addition, in the wiring layer 111, on the surface of the oppositeside of the side where the semiconductor layer 101 is situated, thesupport substrate SS is provided. For example, the substrate formed ofthe silicon semiconductor having the thickness of several hundred μm isprovided as the support substrate SS.

(d) Antireflection Film 50

In the solid-state imaging device 1, as shown in FIG. 3, theantireflection film 50 is provided on the rear surface (the uppersurface in FIG. 3) being the opposite side of the front surface (thelower surface in FIG. 3) whereby each part such as the wiring layer 111is provided in the semiconductor layer 101.

As shown in FIG. 3, the antireflection film 50 includes a firstantireflection film 501 and a second antireflection film 502 and isconfigured so as to prevent the light H incident from the rear surfaceside of the semiconductor layer 101 from being reflected in the rearsurface of the semiconductor layer 101. That is, the material and thefilm thickness of the antireflection film 50 are suitably selected andformed so that the antireflection function is manifested by the opticalinterference action. Herein, it is desirable to form the antireflectionfilm 50 using a material having a high refractive index. Particularly,it is desirable to form the antireflection film 50 using a materialhaving the refractive index of 1.5 or more. In another embodiment, theantireflection film is comprised of the first antireflection film 501which has a antireflection index of 1.5 or more. In another embodiment,each of the first antireflection film 501 and the second antireflectionfilm 502 has a antireflection index of 1.5 or more.

In the antireflection film 50, as shown in FIG. 3, the firstantireflection film 501 is formed so as to cover the rear surface (theupper surface) of the semiconductor layer 101.

Specifically, as shown in FIG. 3, the first antireflection film 501 isprovided so as to cover the portion where the photodiode 21 is formedand the portion where the pixel separation portion 101 pb is formed inthe rear surface of the semiconductor layer 101. Herein, the firstantireflection film 501 is provided so as to have a constant thicknessalong a flat rear surface of the semiconductor layer 101.

In the present embodiment, the first antireflection film 501 is formedto have a film thickness thinner than that of the second antireflectionfilm 502.

Furthermore, the first antireflection film 501 is formed using a highdielectric having a negative fixed electric charge so that theoccurrence of the dark current is suppressed by forming a positiveelectric charge accumulation (hole) accumulation area on the lightsensing surface JS of the photodiode 21. The first antireflection film501 is formed to include at least one of oxide of hafnium, zirconium,aluminum, tantalum, titanium, magnesium, yttrium, lanthanoid, siliconelement or the like. By forming the first antireflection film 501 tohave the negative fixed electric charge, the electric field is added toan interface between it and the photodiode 21 by the negative fixedelectric charge, and thus, the positive electric charge accumulation(hole) accumulation area is formed.

For example, the hafnium oxide film (HfO₂ film) subjected to the filmformation to have a film thickness of 1 to 20 nm is provided as thefirst antireflection film 501.

In the antireflection film 50, as shown in FIG. 3, the secondantireflection film 502 is formed so as to cover the rear surface (theupper surface) of the semiconductor layer 101 via at least one of thefirst antireflection film 501 and the light shielding layer 60. Thesecond antireflection film 502 may be formed to include at least one ofoxide of hafnium, zirconium, aluminum, tantalum, titanium, magnesium,yttrium, lanthanoid, silicon element or the like.

Specifically, as shown in FIG. 3, in the portion where the photodiode 21is formed on the rear surface of the semiconductor layer 101, the secondantireflection film 502 is provided so that the first antireflectionfilm 501 is interposed between it and the semiconductor layer 101.

Furthermore, in the portion where the pixel separation portion 101 pb isformed in the rear surface of the semiconductor layer 101, the secondantireflection film 502 is provided so that both of the firstantireflection film 501 and the light shielding layer 60 are interposedbetween it and the semiconductor layer 101. Herein, the light shieldinglayer 60 is provided in the portion where the pixel separation portion101 pb is provided in the semiconductor layer 101, among the uppersurface of the first antireflection film 501, and the secondantireflection film 502 is provided on the upper surface of the firstantireflection film 501 so as to cover the light shielding layer 60.That is, the light shielding layer 60 having a convex shape is providedon the flat surface of the first antireflection film 501, concave andconvex surfaces are provided, and the second antireflection film 502 isprovided so as to follow the concave and convex surface in a constantthickness.

In the present embodiment, the second antireflection film 502 is formedto have a film thickness thicker than that of the first antireflectionfilm 501.

For example, the hafnium oxide film (HfO₂ film) subjected to the filmformation so that the film thickness totaled with the firstantireflection film 501 becomes 40 to 80 nm is formed as the secondantireflection film 502.

Regarding the first antireflection film 501 and the secondantireflection film 502, various materials can be used besides theabove-mentioned hafnium oxide film (HfO₂ film).

Herein, it is desirable to form the first antireflection film 501 usinga material having a flat band voltage higher than the silicon oxide film(SiO₂ film).

For example, it is desirable to form the first antireflection film 501using a high dielectric material (High-k) as follows. In addition, inthe following description, ΔVfb refers to the value that subtracts theflat band voltage Vfb (SiO₂) of SiO₂ from the flat band voltage Vfb(High-k) of the High-k material (that is, ΔVfb=Vfb (High-k)−Vfb (SiO₂)).

-   -   Al₂O₃ (ΔVfb=4 to 6V)    -   HfO₂ (ΔVfb=2 to 3V)    -   ZrO₂ (ΔVfb=2 to 3V)    -   TiO₂ (ΔVfb=3 to 4V)    -   Ta₂O₅ (ΔVfb=3 to 4V)    -   MgO₂ (ΔVfb=1.5 to 2.5V)

Furthermore, besides the above materials, it is desirable to form thesecond antireflection film 502 using the following material.

-   -   SiN    -   SiON

In the above, the description has been given of the case where thehafnium oxide film (HfO₂ film) is used in regard to both of the firstantireflection film 501 and the second antireflection film 502, thepresent invention is not limited thereto. The above-mentioned variousmaterials can be suitably combined and used.

For example, it is desirable to form the first antireflection film 501and the second antireflection film 502 by the combination of thematerials shown below. In the following description, the left siderefers to the material used upon forming the first antireflection film501 and the right side refers to the material used upon forming thesecond antireflection film 502.

(The material of the first antireflection film 501 and the material ofthe second antireflection film 502)

-   -   (HfO₂, HfO₂)    -   (HfO₂, Ta₂O₅)    -   (HfO₂, Al₂O₃)    -   (HfO₂, ZrO₂)    -   (HfO₂, TiO₂)    -   (MgO₂, HfO₂)    -   (Al₂O₃, SiN)    -   (HfO₂, SiON)

(e) Light Shielding Layer 60

In the solid-state imaging device 1, as shown in FIG. 3, the lightshielding layer 60 is provided at the side of the rear surface (theupper surface in FIG. 3) of the semiconductor layer 101.

The light shielding layer 60 is configured so as to shield a part of theincident light H facing from the upper part of the semiconductor layer101 to the rear surface of the semiconductor layer 101.

As shown in FIG. 3, the light shielding layer 60 is provided in theupper part of the pixel separation portion 101 pb provided in the innerportion of the semiconductor layer 101. Contrary to this, in the upperpart of the photodiode 21 provided in the inner portion of thesemiconductor layer 101, the light shielding layer 60 is not providedbut opened so that the incident light H is incident to the photodiode21.

That is, although it is not shown in FIG. 4, the light shielding layer60 is formed so that the plane shape thereof becomes a grid shape in thesame manner as the pixel separation portion 101 pb.

In the present embodiment, as shown in FIG. 3, the light shielding layer60 is provided to protrude in a convex shape on the upper surface of thefirst antireflection film 501. In addition, the light shielding layer 60is provided so that the upper surface thereof is covered with the secondantireflection film 502 and the convex-shaped side portion comes intocontact with the second antireflection film 502.

The light shielding layer 60 is formed of a light shielding materialthat shields the light. For example, a tungsten (W) film which wassubjected to the film formation to have a film thickness of 100 to 400nm is formed as the light shielding layer 60. In addition, it is alsodesirable to form the light shielding layer 60 by stacking a titaniumnitride (TiN) film and the tungsten (W) film.

(f) The Rest

In addition, as shown in FIG. 3, in the rear surface side of thesemiconductor layer 101, a planarization film HT is provided on theupper surface of the antireflection film 50. On the upper surface of theplanarization film HT, a color filter CF and a micro lens ML areprovided.

For example, the color filter CF includes a red filter layer (notshown), a green filter layer (not shown), and a blue filter layer (notshown), and each filter layer of the three primary colors is disposed tocorrespond to each pixel P in a Bayer arrangement. That is, the colorfilter CF is configured so that different colors of lights penetratetherethrough between the pixels P arranged adjacently to each other inthe horizontal direction x and the vertical direction y.

A plurality of micro lenses ML is disposed to correspond to each pixelP. The micro lens ML is a convex lens protruding in the convex shape inthe rear surface side of the semiconductor layer 101 and is configuredto concentrate the incident light H in the photodiode 21 of each pixelP. For example, the micro lens ML is formed using an organic materialsuch as resin.

(2) Manufacturing Method

A principal part of a method of manufacturing the solid-state imagingdevice 1 will be described.

FIGS. 6 to 10 show a method of manufacturing a solid-state imagingdevice in a first embodiment according to the present invention.

FIGS. 6 to 10 show cross-sections similarly to FIG. 3. The solid-stateimaging device 1 shown in FIG. 3 or the like is manufacturedsequentially via the processes shown in each drawing.

(2-1) Formation of the Photodiode 21 or the Like

Firstly, as shown in FIG. 6, the photodiode 21 or the like is formed.

Herein, by performing the ion implantation of impurities from the frontsurface of the semiconductor substrate formed of a single crystalsilicon semiconductor, the photodiode 21 and the pixel separationportion 101 pb are formed. In addition, after forming the pixeltransistor Tr (shown shown in FIG. 6) on the front surface of thesemiconductor substrate, the wiring layer 111 is formed so as to coverthe pixel transistor Tr. In addition, the support substrate SS isattached to the front surface of the wiring layer 111.

Next, by thinning the semiconductor substrate to have, for example, thethickness of about 10 to 24 μm, the above-mentioned semiconductor layer101 is formed. For example, the thinning is carried out by polishing thesemiconductor substrate according to the CMP method.

(2-2) Formation of First Antireflection Film 501

Next, as shown in FIG. 7, the first antireflection film 501 is formed.

Herein, as shown in FIG. 7, the first antireflection film 501 is formedto cover the rear surface (the upper surface) of the semiconductor layer101.

Specifically, as shown in FIG. 3, on the rear surface of thesemiconductor layer 101, the first antireflection film 501 is providedso as to cover the portion where the photodiode 21 is formed and theportion where the pixel separation portion 101 pb is formed.

For example, by forming the hafnium oxide film (HfO₂ film) to have afilm thickness of 1 to 20 nm under the condition of the film formationtemperature of 200 to 300° C. by an ALD (Atomic Layer Deposition)method, the first antireflection film 501 is provided.

(2-3) Formation of Light Shielding Layer 60

Next, as shown in FIG. 8, the light shielding layer 60 is formed.

Herein, as shown in FIG. 8, the light shielding layer 60 is formed onthe upper surface of the first antireflection film 501 so as to besituated at the upper part of the pixel separation portion 101 pbprovided in the inner portion of the semiconductor layer 101.

For example, after the tungsten (W) film (not shown) is formed on theupper surface of the first antireflection film 501 to have a filmthickness of 100 to 400 nm by the sputtering method, the light shieldinglayer 60 is formed by performing the pattern working to the tungstenfilm. Specifically, by performing the dry etching processing, the lightshielding layer 60 is formed from the tungsten film.

(2-4) Formation of the Second Antireflection Film 502

Next, as shown in FIG. 9, the second antireflection film 502 is formed.

Herein, as shown in FIG. 9, the second antireflection film 502 is formedso that the second antireflection film 502 covers the rear surface (theupper surface) of the semiconductor layer 101 via at least one of thefirst antireflection film 501 and the light shielding layer 60.

Specifically, as shown in FIG. 9, the second antireflection film 502 isformed so that the first antireflection film 501 is interposed in theformation portion of the photodiode 21 and both of the firstantireflection film 501 and the light shielding layer 60 are interposedin the formation portion of the pixel separation portion 101 pb.

For example, by forming the hafnium oxide film (HfO₂ film) by a physicalvapor deposition (PVD) method so that the total film thickness with thefirst antireflection film 501 becomes 40 to 80 nm, the secondantireflection film 502 is formed. The film formation according to thePVD method has the film forming velocity higher than that of the ALDmethod, so that the thick film can be formed within a short time.

(2-5) Formation of the Planarization Film HT

Next, as shown in FIG. 10, the planarization film HT is formed.

Herein, as shown in FIG. 10, the planarization film HT is formed so thatthe upper surface thereof is flat on the second antireflection film 502.

For example, by coating an organic material such as resin by the spincoat method, the planarization film HT is formed.

Next, as shown in FIG. 3, at the rear surface side of the semiconductorlayer 101, the color filter CF and the micro lens ML are provided. Bydoing this, a rear surface irradiation type of CMOS type image sensor iscompleted.

(3) CONCLUSION

As described above, in the present embodiment, a plurality ofphotodiodes 21 that receives the incident light H by the light sensingsurface JS is provided in the inner portion of the semiconductor layer101 to correspond to the plurality of pixels P. In addition, at the rearsurface (the upper surface) side to which the incident light H isincident in the semiconductor layer 101, the antireflection film 50 thatprevents the reflection of the incident light H is provided.Furthermore, at the rear surface side of the semiconductor layer 101,there is provided the light shielding layer 60 where an opening throughwhich the incident light H passes to the light sensing surface JS isformed.

Herein, the antireflection film 50 includes a plurality of films of thefirst antireflection film 501, the second antireflection film 502, andthe first antireflection film 501 is provided to cover the portion wherethe light sensing surface JS and the light shielding layer 60 areprovided on the rear surface. Along with this, in the antireflectionfilm 50, the second antireflection film 502 is formed on the firstantireflection film 501 so as to cover the portion where the lightsensing surface JS is provided on the rear surface. The firstantireflection film 501 has a film thickness thinner than that of thesecond antireflection film 502. In addition, the light shielding layer60 is not provided on the second antireflection film 502 but is providedon the first antireflection film 501 (see FIG. 3).

In this manner, in the present embodiment, only the thin firstantireflection film 501 is provided between the semiconductor layer 101and the light shielding layer 60. For this reason, it is possible tosuppress the incident light H from penetrating the lower portion of thelight shielding layer 60, whereby the incident light H incident to thepixel P can be prevented from being incident to the photodiode 21 of theadjacent different pixel P. That is, the incident light H is incident tothe immediately lower light sensing surface JS, whereby it is possibleto prevent the incident light from being incident to the light sensingsurface JS of the different pixel P that receives the other color oflight.

Thus, in the present embodiment, it is possible to prevent the “mixedcolor” from occurring to improve the color reproducibility in thecaptured color image.

Thus, the present embodiment can improve the image quality.

Moreover, in the present embodiment, the first antireflection film 501is formed using the high dielectric having the negative fixed electriccharge. For this reason, since the positive electric charge accumulation(hole) accumulation area is formed on the light sensing surface JS ofthe photodiode 21, the occurrence of the dark current can be prevented.

Furthermore, in the present embodiment, the antireflection film 50 isformed using a material having the refractive index of 1.5 or more. Forthis reason, since the refractive index difference between it andsilicon (Si) decreases, the effect of the antireflection on the lightsensing surface of silicon can be obtained. Particularly, it isdesirable to use a material having the refractive index of theintermediate refractive index between the refractive index (3.6) of Siof the lower layer and the refractive index (1.45) of SiO₂ of the upperlayer. Specifically, it is desirable to form the antireflection film 50using the SiN film (the refractive index is about 2). Besides, a highrefractive film (the refractive index is about 2.5) such as TiO₂. Thus,it is desirable to form the antireflection film 50 using a materialhaving the refractive index of 1.5 or more and 2.6 or less.

Furthermore, in the present embodiment, the first antireflection film501 is formed by the ALD method. For this reason, since a satisfactorysilicon interface having the small interface state can be formed, theeffect of the dark current reduction can be obtained.

2. SECOND EMBODIMENT (1) Device Configuration or the Like

FIG. 11 is a drawing showing a principal part of a solid-state imagingdevice 1 b in a second embodiment according to the present invention.

FIG. 11 shows the cross-section of the pixel P similarly to FIG. 3.

As shown in FIG. 11, in the present embodiment, an insulation film Z1 isprovided. Along with this, a material of a light shielding layer 60 b isdifferent from that of the first embodiment. Except for this point, thepresent embodiment is the same as the first embodiment. For this reason,description of the overlapped portion will be omitted.

In the present embodiment, unlike the case of the first embodiment, thelight shielding layer 60 b is formed using the Titanium (Ti) film.

Titanium film has a superior close-contact property but has a strongreduction action.

In a case where the titanium film is directly formed as the lightshielding layer 60 b on the hafnium oxide film (HfO₂ film) formed as thefirst antireflection film 501, the reaction occurs between both of thefilms. For this reason, in this case, it is difficult to effectivelysuppress occurrence of the dark current due to the interface state insome cases.

In order to prevent the occurrence of this disadvantage, in the presentembodiment, as shown in FIG. 11, the insulation film Z1 is provided asan intermediate layer between the hafnium oxide film (HfO₂ film) formedas the first antireflection film 501 and the titanium film formed as thelight shielding layer 60 b.

That is, in the present embodiment, the insulation film Z1 is formedusing a material in which the reaction between it and the firstantireflection film 501 hardly occurs compared to the light shieldinglayer 60 b.

For example, the insulation film Z1 is the silicon oxide film and isformed to have a film thickness of 10 nm to 50 nm.

(2) Manufacturing Method

A principal part of a method of manufacturing the solid-state imagingdevice will be described.

FIGS. 12 to 14 are diagrams showing a method of manufacturing asolid-state imaging device 1 b in a second embodiment according to thepresent invention.

Similarly to FIG. 11, FIGS. 12 to 14 show cross-sections, and thesolid-state imaging device shown in FIG. 11 is manufactured sequentiallyvia each process shown in FIGS. 12 to 14.

Even in the case of the present embodiment, similarly to the firstembodiment, as shown in FIGS. 6 and 7, the formation of the photodiode21 or the like and the formation of the first antireflection film 501are carried out.

(2-1) Formation of the Insulation Film Z1 and the Light Shielding Layer60 b

Next, as shown in FIG. 12, the insulation film Z1 and the lightshielding layer 60 b are formed.

Herein, as shown in FIG. 12, the insulation film Z1 and the lightshielding layer 60 are formed on the upper surface of the firstantireflection film 501 so as to be situated at the upper part of thepixel separation portion 101 pb provided in the inner portion of thesemiconductor layer 101.

For example, the silicon oxide film is formed on the upper surface ofthe first antireflection film 501 by the plasma CVD method to have afilm thickness of 10 to 50 nm. Next, for example, the titanium (Ti) filmis formed on the upper surface of the silicon oxide film as theclose-contact layer to have a film thickness of 10 to 50 nm by thesputtering method. Then, the tungsten (W) film as the light shieldinglayer is formed to have the thickness of 100 to 400 nm.

In addition, by performing the pattern working in regard to each of thesilicon oxide film and the tungsten and titanium film, the insulationfilm Z1 and the light shielding layer 60 b are formed. Specifically, byperforming the dry etching process with respect to the silicon oxidefilm, the insulation film Z is subjected to the pattern working.Furthermore, by performing the dry etching process with respect to thetungsten and titanium film, the light shielding layer 60 b is subjectedto the pattern working.

(2-2) Formation of Second Antireflection Film 502

Next, as shown in FIG. 13, the second antireflection film 502 is formed.

Herein, as shown in FIG. 13, the second antireflection film 502 isformed so as to cover the upper surface of the first antireflection film501 on which the insulation film Z1 and the light shielding layer 60 bare formed.

For example, similarly to the case of the first embodiment, by formingthe hafnium oxide film (HfO₂ film) by the physical vapor deposition(PVD) method, the second antireflection film 502 is formed.

As a result, the second antireflection film 502 is formed so that onlythe first antireflection film 501 is interposed in the formation portionof the photodiode 21 and the first antireflection film 501, theinsulation film Z1, and the light shielding layer 60 b are interposed inthe formation portion of the pixel separation portion 101 pb.

(2-3) Formation of the Planarization Film HT

Next, as shown in FIG. 14, the planarization film HT is formed.

Herein, as shown in FIG. 14, the planarization film HT is formed so thatthe upper surface thereof is flat on the second antireflection film 502,similarly to the case of the first embodiment.

Next, as shown in FIG. 11, at the rear surface side of the semiconductorlayer 101, the color filter CF and the micro lens ML are provided. Bydoing this, a rear surface irradiation type of CMOS type image sensor iscompleted.

(3) CONCLUSION

In the present embodiment, similarly to the case of the firstembodiment, only the thin first antireflection film 501 is providedbetween the semiconductor layer 101 and the light shielding layer 60 b(see FIG. 11).

Thus, it is possible to prevent the “mixed color” from occurring toimprove color reproducibility in the captured color image.

Moreover, in the present embodiment, unlike the case of the firstembodiment, the insulation film Z1 is provided between the firstantireflection film 501 and the light shielding layer 60 b (see FIG.11).

For this reason, in the present embodiment, the reaction between thefirst antireflection film 501 and the light shielding layer 60 b isprevented. Thus, even in a case where a material such as titanium havingthe strong reduction action is used for the light shielding layer 60 bto improve the close-contact property, by the action of the negativefixed electric charge included in the first antireflection film 501,occurrence of the dark current caused by the interface state can beeffectively suppressed.

Thus, the present embodiment can improve the image quality.

In addition, besides the above, in a case where the first antireflectionfilm 501 and the light shielding layer 60 b are formed by thecombination of the materials as follows, similarly to the case of thepresent embodiment, it is desirable to provide the insulation film Z1 asthe intermediate layer.

(The material of the first antireflection film 501 and the material ofthe light shielding layer 60 b)=(HfO₂, Ti), (Al₂O₃, Ti), (ZrO₂, Ti)

3. THIRD EMBODIMENT (1) Device Configuration or the Like

FIG. 15 is a diagram showing a principal part of a solid-state imagingdevice 1 c in a third embodiment according to the present invention.

FIG. 15 shows the cross-section of the pixel P similarly to FIG. 3.

As shown in FIG. 15, in the present embodiment, the configurations of anantireflection film 50 c and a light shielding layer 60 c are differentfrom those of the first embodiment. Besides this point, the presentinvention is the same as the first embodiment. For this reason,descriptions of the overlapped portions will be omitted.

(a) Antireflection Film 50 c

As shown in FIG. 15, similarly to the case of the first embodiment, theantireflection film 50 c includes a plurality of films of a firstantireflection film 501 and a second antireflection film 502 c.

In the antireflection film 50 c, similarly to the case of the firstembodiment, the first antireflection film 501 is provided on the rearsurface (the upper surface in FIG. 15) of the semiconductor layer 101.In addition, as shown in FIG. 15, the second antireflection film 502 cis provided so that the first antireflection film 501 is interposed inthe portion where the photodiode 21 is formed on the rear surface of thesemiconductor layer 101.

However, in the portion where the pixel separation portion 101 pb isformed on the rear surface of the semiconductor layer 101, unlike thecase of the first embodiment, the second antireflection film 502 c isnot provided.

(b) Light Shielding Layer 60 c

As shown in FIG. 15, similarly to the first embodiment, the lightshielding layer 60 c is formed in the portion where the pixel separationportion 101 pb is provided in the semiconductor layer 101 among theupper surface of the first antireflection film 501. However, the secondantireflection film 502 c is not provided so as to cover the lightshielding layer 60 c.

(c) The Rest (Manufacturing Method or the Like)

In the present embodiment, after forming the first antireflection film501 and before forming the light shielding layer 60 c, the secondantireflection film 502 c is formed. Herein, by forming a material filmfor forming the second antireflection film 502 c is formed on the uppersurface of the first antireflection film 501 and then performing thepattern working of the material film, the second antireflection film 502c is formed. That is, by etching the material film for forming thesecond antireflection film 502 c so that the front surface of theportion where the light shielding layer 60 c is formed is exposed amongthe upper surface of the first antireflection film 501 to form a grooveTR, the second antireflection film 502 c is formed.

Next, the material film for forming the light shielding layer 60 c isformed on the second antireflection film 502 c so as to embed the innerportion of the groove TR. In addition, by performing the planarizationprocess so that the upper surface of the second antireflection film 502c is exposed, the light shielding layer 60 c is formed.

The respective portions are formed as above to complete the solid-stateimaging device 1 c.

In the present embodiment, in order to form the respective portions asabove, it is desirable to form the first antireflection film 501 and thesecond antireflection film 502 c by a material in which the etchingselection ratio between them becomes larger. Moreover, it is desirableto form the light shielding layer 60 c by a material that can be easilyembedded in the groove TR.

(2) CONCLUSION

In the present embodiment, similarly to the case of the firstembodiment, only the thin first antireflection film 501 is formedbetween the semiconductor layer 101 and the light shielding layer 60 c(see FIG. 15).

Thus, it is possible to prevent the occurrence of the “mixed color” toimprove color reproducibility in the captured color image.

In the present embodiment, unlike the case of the first embodiment, thesecond antireflection film 502 is not formed so as to cover the uppersurface of the light shielding layer 60 c. The light shielding layer 60c is formed so as to be buried in the groove TR provided in the secondantireflection film 502 (see FIG. 15).

For this reason, in the present embodiment, the front surfaces of thelight shielding layer 60 c and the second antireflection film 502 areflat (see FIG. 15). Thus, the planarization film HT to be stacked on theupper layer can be thinned and the intensity of the light H incident tothe light sensing surface JS can be improved, so that high sensitivitycan be realized.

Thus, the present embodiment can improve the image quality.

4. FOURTH EMBODIMENT (1) Device Configuration or the Like

FIG. 16 is a diagram showing a principal part of a solid-state imagingdevice 1 d in a fourth embodiment according to the present invention.

FIG. 16 shows the cross-section of the pixel P, similarly to FIG. 3.

As shown in FIG. 16, in the present embodiment, the configurations of anantireflection film 50 d and a light shielding layer 60 d are differentfrom those of the first embodiment. Besides this point, the presentinvention is the same as the first embodiment. For this reason,descriptions of the overlapped portions will be omitted.

(a) Antireflection Film 50 d

As shown in FIG. 16, similarly to the case of the first embodiment, theantireflection film 50 d includes a plurality of films of a firstantireflection film 501 d and a second antireflection film 502 d.

As shown in FIG. 16, in the antireflection film 50 d, similarly to thefirst embodiment, the first antireflection film 501 d is provided so asto cover the rear surface (the upper surface) side of the semiconductorlayer 101. That is, the first antireflection film 501 d is provided soas to cover the portion where the photodiode 21 is formed and theportion where the pixel separation portion 101 pb is formed in the rearsurface side of the semiconductor layer 101.

However, in the present embodiment, unlike the first embodiment, therear surface side of the semiconductor layer 101 is not flat but has agroove TRd provided therein and becomes a concave and convex surface,and the first antireflection film 501 d is formed in a regular thicknessso as to cover the concave and convex surfaces.

In the antireflection film 50 d, as shown in FIG. 16, the secondantireflection film 502 d is provided so as to cover the rear surface(the upper surface) of the semiconductor layer 101 via at least one ofthe first antireflection film 501 d and the light shielding layer 60 d.

Specifically, as shown in FIG. 16, in the portion where the photodiode21 is formed on the rear surface of the semiconductor layer 101,similarly to the first embodiment, the second antireflection film 502 dis provided so that the first antireflection film 501 d is interposedbetween it and the semiconductor layer 101.

Furthermore, in the portion where the pixel separation portion 101 pb isformed on the rear surface of the semiconductor layer 101, the secondantireflection film 502 is provided so that both of the firstantireflection film 501 d and the light shielding layer 60 d areinterposed between it and the semiconductor layer 101.

In the present embodiment, as shown in FIG. 16, unlike the firstembodiment, the rear surface side of the semiconductor layer 101 has thegroove TRd provided therein, the first antireflection film 501 d coversthe surface of the groove TRd, and the light shielding layer 60 d isprovided in the inner portion of the groove TRd. For this reason, thesecond antireflection film 502 d is provided on the upper surface of thefirst antireflection film 501 d so as to interpose the light shieldinglayer 60 d thus formed therebetween. That is, the second antireflectionfilm 502 d is formed in the regular thickness so as to follow the flatsurface on which the first antireflection film 501 d and the lightshielding layer 60 d are provided.

(b) Light Shielding Layer 60 d

As shown in FIG. 16, the light shielding layer 60 d is provided at theupper part of the pixel separation portion 101 pb provided in the innerportion of the semiconductor layer 101.

In the present embodiment, as shown in FIG. 16, the groove TRd isprovided in the portion where the pixel separation portion 101 pb isprovided on the rear surface side of the semiconductor layer 101, andthe first antireflection film 501 d is provided so as to cover thesurface of the groove TRd. In addition, the light shielding layer 60 dis provided so as to be buried in the inner portion of the groove TRdcovered with the first antireflection film 501 d.

In addition, the upper surface of the light shielding layer 60 d iscovered with the second antireflection film 502 d.

(c) The Rest (Manufacturing Method or the Like)

In the present embodiment, before forming the first antireflection film501, the groove TRd is formed in the portion where the pixel separationportion 101 pb is provided in the rear surface side of the semiconductorlayer 101. In addition, the first antireflection film 501 is formed onthe rear surface of the semiconductor layer 101 so as to cover thegroove TRd.

Next, the material film for forming the light shielding layer 60 d isformed on the first antireflection film 501 d so as to bury the innerportion of the groove TR. In addition, by performing the planarizationprocess so that the upper surface of the first antireflection film 501 dis exposed, the light shielding layer 60 d is formed.

The second antireflection film 502 d is formed so as to cover the firstantireflection film 501 d and the light shielding layer 60 d.

The respective portions are formed as above to complete the solid-stateimaging device 1 d.

(2) CONCLUSION

In the present embodiment, the light shielding layer 60 d is provided inthe inner portion of the groove TRd provided in the formation portion ofthe pixel separation portion 101 pb (see FIG. 16).

For this reason, the light shielding layer 60 d can shield the lightthat is incident from the pixel P to the photodiode 21 of the adjacentdifferent pixel P. Thus, it is possible to prevent the occurrence of the“mixed color” to improve the color reproducibility in the captured colorimage.

In the present embodiment, the front surface of the semiconductor layer101 is flat, and thus, the planarization film HT to be stacked on theupper part thereof can be thinned and the intensity of the light Hincident to the light sensing surface JS can be improved. Thus, highsensitivity can be realized.

Upon carrying out the present invention, various modified examples canbe adopted without being limited to the above-mentioned embodiments.

For example, although, in the above-mentioned embodiment, the case wherethe antireflection film 50 is constituted by two films has beendescribed, the present invention is not limited thereto. If it isconfigured so that the antireflection film 50 includes the firstantireflection portion covering the formation portion of the lightsensing surface and the light shielding surface, and the secondantireflection portion covering the formation portion of the lightsensing portion JS on the first antireflection portion, among thesurfaces to which the incident light is incident, the number of thefilms is not limited.

In the above-mentioned embodiments, the case of the “rear surfaceirradiation type” has been described, but the present invention is notlimited thereto. The present invention may be applied to the case of the“front surface irradiation type”.

In the above-mentioned embodiment, the case where four types of thetransmission transistor, the amplification transistor, the selectiontransistor, and the reset transistor are provided as the pixeltransistor has been described, but the present invention is not limitedthereto. For example, the present invention may be applied to a casewhere three types of the transmission transistor, the amplificationtransistor, and the reset transistor are provided as the pixeltransistor.

In the above-mentioned embodiment, the description has been given of thecase where one transmission transistor, one amplification transistor,one selection transistor, and one reset transistor are provided withrespect to one photodiode, but the present invention is not limitedthereto. For example, the present invention may be applied to the casewhere one amplification transistor, one selection transistor, and onereset transistor are provided with respect to a plurality ofphotodiodes.

Furthermore, in the above-mentioned embodiments, the description hasbeen given of the case where the present invention is applied to acamera, but the present invention is not limited thereto. The presentinvention may be applied to other electronic equipment including asolid-state imaging device such as a scanner or a copier.

In addition, in the above-mentioned embodiments, the solid-state imagingdevices 1, 1 b, 1 c and 1 d correspond to the solid-state imaging deviceof the present invention. Moreover, in the above-mentioned embodiments,the photodiode 21 corresponds to the photoelectric conversion portion ofthe present invention. In the above-mentioned embodiments, the camera 40corresponds to the electronic equipment of the present invention. In theabove-mentioned embodiments, the semiconductor layer 101 corresponds tothe semiconductor layer of the present invention. In the above-mentionedembodiments, the antireflection films 50, 50 c and 50 d correspond tothe antireflection film of the present invention. In the above-mentionedembodiments, the first antireflection films 501 and 501 d correspond tothe first antireflection portion of the present invention. In theabove-mentioned embodiments, the second antireflection films 502, 502 cand 502 d correspond to the second antireflection portion of the presentinvention. In the above-mentioned embodiments, the light shieldinglayers 60, 60 b, 60 c and 60 d correspond to the light shielding layerof the present invention. In the above-mentioned embodiments, the lightsensing surface JS corresponds to the light sensing surface of thepresent invention. In the above-mentioned embodiments, the pixel Pcorresponds to the pixel of the present invention. In theabove-mentioned embodiments, the insulation layer Z1 corresponds to theintermediate layer of the present invention.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. A solid state imaging device comprising: a semiconductor layercomprising a plurality of photodiodes; a first antireflection filmlocated over a first surface of the semiconductor layer; a secondantireflection film located over the first antireflection film; and alight shielding layer having side surfaces which are adjacent to atleast one of the first and the second antireflection film.
 2. The solidstate imaging device of claim 1 wherein the light shielding layer islocated between the first antireflection film and the secondantireflection film.
 3. The solid state imaging device of claim 2including an intermediate layer located between the first antireflectionfilm and the light shielding layer.
 4. The solid state imaging device ofclaim 1 wherein the light shielding layer is embedded in the secondantireflection film.
 5. The solid state imaging device of claim 1including a separation region between each of the plurality ofphotodiodes.
 6. The solid state imaging device of claim 5 wherein thelight shielding layer is located over the separation region.
 7. Thesolid state imaging device of claim 5 including a trench located in eachof the separation regions, wherein, the light shielding layer is locatedinside the trench.
 8. The solid state imaging device of claim 1 whereinthe photodiode has a first surface which receives light.
 9. The solidstate imaging device of claim 8 wherein the first antireflection filmand the second antireflection film are located over the first surface ofthe photodiode.
 10. The solid state imaging device of claim 1 whereinthe thickness of the first antireflection film is smaller than thethickness of the second antireflection film.
 11. The solid state imagingdevice of claim 1 wherein the light shielding layer has a substantiallyconvex shape.
 12. The solid state imaging device of claim 1 wherein thefirst antireflection film includes at least one of an oxide of hafnium,zirconium, aluminum, tantalum, titanium, magnesium, yttrium, lanthanoidor silicon element.
 13. The solid state imaging device of claim 1wherein the second antireflection film includes at least one of an oxideof hafnium, zirconium, aluminum, tantalum, titanium, magnesium, yttrium,lanthanoid or silicon element.
 14. The solid state imaging device ofclaim 1 wherein, the first antireflection film has a refraction index of1.5 or more.
 15. The solid state imaging device of claim 14 wherein thesecond antireflection film has a refraction index of 1.5 or more
 16. Thesolid state imaging device of claim 1 including a wiring layer locatedover a second surface of the semiconductor layer opposite the firstantireflection film and the second antireflection film.
 17. The solidstate imaging device of claim 15 including a transistor located over thesecond surface of the semiconductor layer.
 18. The solid state imagingdevice of claim 17 wherein the transistor transfers an electric chargefrom the photodiode to a transmission line.
 19. A method formanufacturing a solid state imaging device comprising the steps of:forming a semiconductor layer comprising a plurality of photodiodes;forming a first antireflection film over a first surface of thesemiconductor layer; forming a second antireflection film over the firstantireflection film; and forming a light shielding layer having sidesurfaces, wherein, the side surfaces are adjacent to at least one of thefirst antireflection film and the second antireflection film.
 20. Themethod of claim 19 wherein the second antireflection film is formedafter forming the light shielding layer.
 21. The method of claim 19wherein the light shielding layer is formed after forming the secondantireflection film.
 22. The method of claim 19 wherein the lightshielding layer is located between the first antireflection film and thesecond antireflection film.
 23. The method of claim 22 including thestep of forming an intermediate layer located between the firstantireflection film and the light shielding layer.
 24. The method ofclaim 22 wherein the light shielding layer is embedded in the secondantireflection film.
 25. The method of claim 19 including the step offorming a separation region between each of the plurality ofphotodiodes.
 26. The method of claim 19 wherein the light shieldinglayer is located over the separation region.
 27. The method of claim 25including a trench located in each of the separation regions, wherein,the light shielding layer is located inside the trench.
 28. The methodof claim 19 wherein the photodiode has a first surface which receiveslight.
 29. The method of claim 28 wherein the first antireflection filmand the second antireflection film are located over the first surface ofthe photodiode.
 30. The method of claim 19 wherein the thickness of thefirst antireflection film is smaller than the thickness of the secondantireflection film.
 31. The method of claim 19 wherein the lightshielding layer has a substantially convex shape.
 32. The method ofclaim 19 wherein the first antireflection film includes at least one ofan oxide of hafnium, zirconium, aluminum, tantalum, titanium, magnesium,yttrium, lanthanoid or silicon element.
 33. The method of claim 19wherein the second antireflection film includes at least one of an oxideof hafnium, zirconium, aluminum, tantalum, titanium, magnesium, yttrium,lanthanoid element or silicon element.
 34. The method of claim 19wherein the first antireflection film has a refraction index of 1.5 ormore.
 35. The method of claim 34 wherein the second antireflection filmhas a refraction index of 1.5 or more.
 36. The method of claim 19including the step of forming a wiring layer over a second surface ofthe semiconductor layer opposite the first antireflection film and thesecond antireflection film.
 37. The method of claim 36 including forminga transistor over the second surface of the semiconductor layer.
 38. Themethod of claim 37 wherein the transistor transfers an electric chargefrom the photodiode to a transmission line.
 39. An electronic apparatuscomprising: a semiconductor layer including a plurality of photodiodes;a first antireflection film on a first surface of the semiconductorlayer; a second antireflection film over the first antireflection film;a light shielding layer adjacent the first antireflection film; and aphotodiode layer having a side surface adjacent at least the secondantireflection film.